The present invention relates to a coagulant for oils, especially oils spilled on the water surfaces of seas, harbours, rivers, lakes, swamps and the like, and also to a process for the preparation of such oil coagulant.
Recently, occurrence of accidents of outflow of crude oil and refined oil into seas, harbours, rivers, lakes, swamps and the like becomes intensive with developments in excavation of oil wells, transportation of crude oils and petrochemical industries. Oil spill into seas or the like results in occurrence of fires and pollution of seas. Accordingly, attempts have been made to prevent expansion of spilled oils in seas or the like by using oil treating agents, for example, oil coagulants.
Oil treating agents that are now used to cope with accidents of oil spills are emulsifiers having a function of dispersing spilled oils into sea water. These agents do not remove oils acting as the contamination sources and there is involved a risk that toxicities of these agents have bad influences on marine products. Accordingly, inhibition of use of these oil treating agents is now demanded, and the Transport Ministry of the Japanese Government has issued an official notice inhibiting use of oil treating agents having an emulsifying action "unless fires and other accidents causing a loss of lives or a serious damage of property occur or there is a risk of occurrence of such accidents".
Under such background, it has been eagerly desired to develop and use an oil treating agent having novel characteristics, namely an oil treating agent which can be used instead of the conventional oil treating agents for prevention occurrence of fires when oils spill and which has no bad influences on marine products and enables recovery of oils acting as contamination sources.
As an oil treating agent meeting such desire, we have already developed and published a protein type spilled oil treating agent (Japanese Pat. No. 822,527). This oil treating agent has a considerable effect but it leaves much room for improvement in properties thereof. For example, when this treating agent is sprinkled on the water surface on which an oil flows out, the water layer is made turbid more or less by application of the agent, though the oil is coagulated in the gel-like form to prevent occurrence of a fire or expansion of the oil and facilitate recovery of the oil and the agent has other characteristic properties such as the absence of any toxicity. Of course, this turbidity-causing component is quite harmless and has no bad influences on marine products. However, elimination of this action of rendering water turbid is desired. Accordingly, it is eagerly desired to develop an oil coagulant which does not render water turbid or show any emulsifying action when applied to the water surface, and which can coagulate a spilled oil completely and can be prepared very easily.
As a result of our researches made with a view to developing such oil coagulant and establishing a process for the preparation thereof, we have now completed the present invention.